sodium disorders hyponatremia l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Sodium Disorders: Hyponatremia PowerPoint Presentation
Download Presentation
Sodium Disorders: Hyponatremia

Loading in 2 Seconds...

play fullscreen
1 / 37

Sodium Disorders: Hyponatremia - PowerPoint PPT Presentation


  • 535 Views
  • Uploaded on

Sodium Disorders: Hyponatremia. William Harper, MD, FRCPC Endocrinology & Metabolism Assistant Professor of Medicine McMaster University. Normal Serum [Na] (135-145 mEq/L) Closely Guarded. ADH (pM). ↓ ECFv. Thirst. 5. 0. 130. 135. 140. 145. P Na (mEq/L).

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Sodium Disorders: Hyponatremia' - Anita


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
sodium disorders hyponatremia

Sodium Disorders: Hyponatremia

William Harper, MD, FRCPC

Endocrinology & Metabolism

Assistant Professor of Medicine

McMaster University

slide3

Normal Serum [Na] (135-145 mEq/L) Closely Guarded

ADH

(pM)

↓ ECFv

Thirst

5

0

130

135

140

145

PNa (mEq/L)

slide4

What is Appropriate Urine Concentration?

  • Complete DI
  • Defective osmoreceptor, normal AVP release to ECFv contraction
  • High-set osmoreceptor: AVP release is sluggish/delayed
  • AVP release at normal Posm but subnormal in amount
osmolality
Osmolality
  • Plasma Osmolality:

Posm = 2 (Na) + glucose + urea

Normal = 2 (140) + 5 + 5 = 290 (275-290 mM)

  • Urine Osmolality:
      • Normal: 400-500 mM
          • Maximal dilution 50-100 mM (USG 1.002-1.003)
          • Maximal concentration 900-1200 mM (USG 1.030-1.040)
      • Concentrated Urine: > 500 mM (at least!), USG > 1.017

i.e. UOSM > POSM is not enough to R/O Diabetes Insipidus

urine specific gravity u sg
Urine Specific Gravity USG
  • Estimates solute concentration of urine on basis of weight as compared with an equal volume of distilled water
      • Normal Posm is 0.8-1.0% heavier than water so PSG = 1.008-1.010
  • Each ↑ in UOSM 30-35 mM ↑ USG by 0.1% (0.001)
  • Therefore, USG of 1.010 ~ UOSM 300-350 mM
  • Larger MW urinary OSM (glucose, radiocontrast, carbenicillin) if present will falsely elevate USG
  • Nothing falsely lowers USG
slide7

Hyponatremia

Serum OSM

Normal

High

Low

Marked hyperlipidemia

(lipemia, TG >35mM)

Hyperproteinemia

(Multiple myeloma)

Hyperglycemia

Mannitol

Hypotonic

Hyponatremia

  • *Note: all have ↑ADH
  • SIADH: inappropriate
  • Rest: appropriate

ECFv *

Low

High

Normal

  • CHF
  • Cirrhosis
  • Nephrosis
  • Hypothyroidism
  • AI
  • SIADH
  • Reset Osmostat
  • Water Intoxication
  • 1° Polydipsia
  • TURP post-op
  • Renal loss (UNa > 20)
    • Diuretics
      • Thiazide
      • K-sparing
    • ACE-I, ARB
    • IV RTA, Hypoaldo
    • Cerebral salt wasting
  • Extra-renal loss (UNa <10)
    • Bleeding
    • Burns
    • GI (N/V, diarrhea)
    • Pancreatitis
rx hyponatremia
Rx Hyponatremia
  • Na deficit = 0.6 x wt(kg) x (desired [Na] - actual [Na])

(mmol)

  • When do you need to Rx quickly?
    • Acute (<24h) severe (< 120 mEq/L) Hyponatremia
      • Prevent brain swelling or Rx brain swelling
    • Symptomatic Hyponatremia (Seizures, coma, etc.)
      • Alleviate symptoms
  • “Quickly”: 3% NS, 1-2 mEq/L/h until:
      • Symptoms stop
      • 3-4h elapsed and/or Serum Na has reached 120 mEq/L
  • Then SLOW down correction to 0.5 mEq/L/h with 0.9% NS or simply fluid restriction. Aim for overall 24h correction to be < 10-12 mEq/L/d to prevent myelinolysis
rx hyponatremia example
Rx Hyponatremia (Example)
  • Na deficit(mmol) = 0.6 x wt(kg) x (desired [Na] - actual [Na])
  • 60 kg women, serum Na 107, seizure recalcitrant to benzodiazepines.
  • Na defecit = 0.6 x (60) x (120 – 107) = 468 mEq
  • Want to correct at rate 1.5 mEq/L/h: 13/1.5 = 8.7h
  • 468 mEq / 8.7h = 54 mEq/h
  • 3% NaCl has 513 mEq/L of Na
  • 54 mEq/h = x

513 mEq 1L

  • x = rate of 3% NaCl = 105 cc/h over 8.7h to correct serum Na to 120 mEq/h
  • Note: Calculations are always at best estimates, and anyone getting hyponatremia corrected by IV saline (0.9% or 3%) needs frequent serum electrolyte monitoring (q1h if on 3% NS).
rx hyponatremia10
Rx Hyponatremia
  • Rx slowly (correct < 0.5 mEq/L/h, 10-12 mEq/L/d)
    • Symptomatic/Acute: rapid Rx has resolved symptoms and brought serum Na up to 120 mEq/L
    • Asymptomatic, mild, chronic hyponatremia
    • Want to prevent myelinolysis
      • Increased risk: Women, alcoholics, malnourished
  • ECFv contracted
      • Bolus NS until BP, HR, JVP stable
      • Then correct slowly with 0.9% NS or po salt
  • ECFv Normal or ECFv Overloaded
      • Fluid Restriction alone (exception: SAH, HI, post-neurosurgery)
      • i.e. they do NOT need any IV or po salt!
siadh ddx
SIADH Ddx
  • Intracranial disease
  • Pulmonary disease
  • Chest wall disorder (surgery, VZV)
  • Severe pain or emotional distress
  • Severe N/V
  • Ectopic ADH: Small cell lung cancer
  • Drugs: opiods, carbamazepine, chlorpropamide, cyclophosphamide, cisplatin, vincristine, vinblastine, amitriptylline, SSRI, neuroleptics, bromocriptine, ecstasy (MDMA)
siadh
SIADH

Diagnosis

  • Normal ECFv (or slightly increased)
  • Hypothyroidism & AI ruled out
  • ↓ serum Na/OSM
  • UOSM > 100 mM, UNa > 40 mEq/L
  • Low plasma uric acid (< 238 umol/L)

Treatment

  • Fluid Restriction
  • Oral Salt, Hi-protein diet or Urea(30 g/d): promote solute diuresis
  • Lasix 20 mg po od-bid: Loop direct diminishes medullary gradient
  • Demeclocycline 300-600 mg bid (can be nephrotoxic)
  • Lithium (induces NDI)
  • IV salt solution:
      • Rarely if ever needed (i.e. only if symptomatic with SZ/coma)
      • Solution given must be of greater OSM than UOSM or in long run will just make hyponatremia worse (often IV NS not sufficient)
siadh example
SIADH: Example
  • UOSM fixed 600 mM due to ADH action
  • 1L NS given: 300 mM (154 mM each of Na and Cl)
  • All sodium will be excreted as renal sodium handling is intact in SIADH.
  • 300 mmoles of osmols given excreted in 500cc urine (300mmoles/500mL = 600 mM)
  • Therefore net gain of 500 cc free water!
  • 1L 3% saline given: 1026 mmoles
  • Excreted in 1.7L to keep UOSM 600 mM
  • Therefore net loss of 700 cc free water!
  • NOT advocating use of any IV NS (0.9% or 3%) in SIADH unless absolutely neccesary (i.e. SZ, coma). Most SIADH hyponatremia is chronic and should be corrected slowly with fluid restriction ONLY.
reset osmostat
Reset Osmostat
  • 25-30% of circumstances which cause SIADH
  • Downward resetting of the threshold for both ADH release and thirst.
  • Mild asymptomatic hyponatremia (Na 125-135 mEq/L)
  • Distinguish from SIADH by observing response to water load (10-15 mL/kg po or IV)
  • Normal subjects and those with reset osmostat will secrete the entire water load over 4h without any worsening of the hyponatremia
  • Attempts to correct hyponatremia in reset osmostat are not needed and will cause severe thirst
cerebral salt wasting
Cerebral Salt Wasting
  • Cerebral disease (particularly SAH)
  • Mimics SIADH with hyponatremia except primary defect is salt wasting not water retention.
  • Circulating factor which impairs renal tubular fn.
      • Atrial natriuretic peptide?
      • Brain natriuretic peptide?
      • Endogenous ouabain?
  • Plasma urate variable (normal or even lower than SIADH)
  • Treatment is NS to correct ECFv contraction
rx hyponatremia acute sah head injury
Rx Hyponatremia: acute SAH/Head injury
  • May have SIADH, CSW or Both!
      • Often difficult to tell which
      • Fluid restriction inappropriate for CSW as may exacerbate ECFv contraction and precipitate cerebral vasospasm and subsequent cerebral infarction
      • IV NS inappropriate for SIADH if UOSM > 300 mM (will make hyponatremia worse)
  • Rx with IV NS:
      • Start with 0.9% NS (as per hypervolemic therapy to prevent cerebral vasospasm)
      • If hyponatremia worsens on 0.9% NS (due to an SIADH component to hyponatremia) consider switch to 3% NS
      • Goal: 0.5 mEq/L/h (only if symptomatic 1-2 mEq/L/h)
  • Fludrocortisone
      • 0.1-0.4 mg/d
      • May also be beneficial in recalcitrant cases to alleviate CSW.
indications for 3 nacl
Indications for 3% NaCl
  • Symptomatic hyponatremia (SZ, coma)
  • Acute severe hyponatremia (<24h, < 120 mEq/L)
  • SAH with hyponatremia worsening on 0.9% NaCl
sodium disorders hypernatremia

Sodium DisordersHypernatremia

William Harper, MD, FRCPC

Endocrinology & Metabolism

Assistant Professor of Medicine

McMaster University

diabetes insipidus
Diabetes Insipidus

Polyuria: > 3 L/d +Polydipsia: > 3.5 L/d

Ddx

  • Diabetes Mellitus
  • Hypercalcemia
  • Solute diuresis:
      • Volume expansion 2° saline loading
      • High-protein feeds (urea as osmotic agent)
      • Post-obstructive diuresis
  • Diabetes Insipidus:
      • Central (CDI)
      • Nephrogenic (NDI)
  • Primary (Psychogenic) Polydipsia
diabetes insipidus ddx
Central (CDI)

Idiopathic

autoimmune

Neurosurgery, head trauma

Cerebral hypoperfusion

Tumor

Craniopharyngioma, pituitary adenoma, suprasellar meningioma, pineal gland, metastasis

Infiltration

Fe, Sarcoid, Histiocytosis X

Nephrogenic (NDI)

X-linked recessive

Hypokalemia

Hypercalcemia (2° to HPT in particular)

Renal disease: after ATN, postobstructive uropathy, RAS, renal transplant, amyloid, Sickle cell anemia

Sjogren’s

Drugs:

Lithium, 20% of chronic users

Demeclocycline, amphotericin, colchicine

Diabetes Insipidus Ddx
slide24

What is Appropriate Urine Concentration?

  • Complete DI
  • Defective osmoreceptor, normal AVP release to ECFv contraction
  • High-set osmoreceptor: AVP release is sluggish/delayed
  • AVP release at normal Posm but subnormal in amount
diabetes insipidus25
Diabetes Insipidus
  • Intact thirst & access to water
      • Hi-normal serum sodium (142-145 mEq/L)
      • Polydipsia (crave cold fluids)
      • Polyuria, Nocturia  sleep disturbance
      • 1° treatment is pharmacological
  • Impaired thirst or access to water:
      • Hypernatremia
      • Insufficiently concentrated urine
      • 1° treatment is free water (enteral or IV D5W)
diabetes insipidus26
Diabetes Insipidus
  • Healthy out-patients
  • DI with Intact thirst or access to water
      • Hi-normal serum sodium (142-145 mEq/L)
      • Polydipsia (crave cold fluids)
      • Polyuria, Nocturia  sleep disturbance
  • 1˚ Psychogenic Polydipsia
      • Low-normal serum sodium (135-137 mEq/L)
      • Anxious middle-aged women
      • Psychiatric illness, phenothiazine (dry mouth)
1 polydipsia what came first
1˚ Polydipsia: “What came first?”

The Polyuria or the Polydipsia?

The Chicken or the Egg? (Egg)

water deprivation test
Water Deprivation Test
  • Hold water intake for 2-3h prior to coming in.
  • Continue to hold water & Monitor:
      • Urine volume, UOSM q1h
      • Serum Na, OSM q2h
  • If serum OSM/sodium do not rise above normal ranges & UOSM reaches 600  1˚ Polydipsia
  • If serum OSM reaches 295-300 mM & UOSM doesn’t ↑
      • Diabetes Insipidus established
      • Endogenous ADH should be maximal, check serum ADH
        • 2 green rubber stopper tubes, pre-chilled, on ice, need biochemist
      • Give DDAVP 10 ug IN
        • CDI: UOSM ↑ by 100-800% (complete CDI), ↑ by 15-50% (partial CDI) with absolute UOSM > 345mM
        • NDI: UOSM ↑ by up to < 9%, sometimes ↑ as high as 45% but absolute UOSM always < isotonic (290 mM)
diabetes insipidus30
Diabetes Insipidus
  • Back to in-patients!
  • Impaired thirst or access to water
      • Elevated serum sodium/OSM
      • UOSM < 500 mM, USG < 1.017
  • If serum sodium/OSM not elevated
      • Not DI!
      • UOSM and USG are irrelevant
pituitary surgery
Pituitary Surgery
  • Triphasic response to surgery
  • Phase 1: DI
      • Axonal injury 2° surgery/swelling
      • Begins after POD #1 (pre-existing DI can occur earlier)
      • Lasts 1-5d
  • Phase 2: SIADH
      • Axonal necrosis of AVP secreting neurons with uncontrolled AVP release
      • Lasts 1-5 days
  • Phase 3: DI
      • Axonal death with cessation of AVP production
      • Usually permanent
slide32

PNa

(mEq/L)

U/O

(cc/h)

400

150

U/O #1

100

100

50

50

U/O #2

1

6

11

POD #

slide33

PNa

(mEq/L)

U/O

(cc/h)

400

Na #1

150

U/O #1

100

100

50

50

1

6

11

POD #

slide34

PNa

(mEq/L)

U/O

(cc/h)

400

150

Na #2

100

100

50

50

U/O #2

1

6

11

POD #

slide35

#1 DI

#2 Normal

PNa

(mEq/L)

U/O

(cc/h)

400

Na #1

150

Na #2

U/O #1

100

100

50

50

U/O #2

1

6

11

POD #

treatment of di
Treatment of DI
  • Rx Dehydration
      • NS initially if ECFv contraction
      • Then IV D5W or enteral free water to lower serum [Na]
          • 1-2 mEq/h if Na > 160, symptomatic (coma, SZ), acute
          • Otherwise 0.5-1.0 mEq/h
      • Insensible losses? (0.5 L/d)
      • Do NOT replace U/O if giving DDAVP
  • DDAVP (Desmopressin)
      • Reduces U/O and therefore simplifies fluid therapy
      • Long t½: duration 8-12h, up to 24h
      • Therefore use judiciously
          • DDAVP 1ug IV/SC x 1
          • Only repeat if breaks-thru again (i.e. becomes hypernatremic with dilute polyuria)
          • Once nasal mucosa stable can switch to intranasal
          • Also oral form DDAVP now available

DDAVP: 1ug IV/SC = 10 ug IN = 0.1 mg PO

treatment of di37
Treatment of DI
  • AVP, Aqueous vasopressin (Pitressin)
      • Only parenteral form, 5-10 U SC q2-4h
      • Lasts 2-6h
      • Can cause HTN, coronary vasospasm
  • Chlorpropamide(OHA which stimulates AVP secretion)
      • 100-500 mg po OD-bid
      • Only useful for partial DI, can cause hypoglycemia
  • HTCZ(induces volume contraction which diminishes free water excretion)
      • 50-100 mg OD-bid
      • Mainstay of Rx for chronic NDI
  • Amiloride(blunts Lithium uptake in distal tubules & collecting ducts)
      • 5-20 mg po OD-bid
      • Drug of choice for Lithium induced DI
  • Indomethacin 100-150 mg po bid-tid (PGs antagonize AVP action)
  • Clofibrate 500 mg po qid (augments AVP release in partial CDI)
  • Tegretol 200-600 mg po od (augments AVP release in partial CDI)